1. Field
Aspects of the invention relate to an airbag cover, in particular for use in motor vehicles, having a molding and a visible cover over the molding, with a suitable tear line in the cover.
2. Discussion of Related Art
In some motor vehicles, large areas of the interior trim such as for example the steering wheel, dashboard and door trims, are covered with leather or a leather-like material for decorative reasons. The leather or leather-like material also serves as a visible cover of the parts of the vehicle interior, including the airbag module.
Usually an airbag is disposed below a molding finished with a visible cover, where the molding is designed so that on triggering of the airbag, parts of the molding move along pre-defined fold or tear lines so that suitable deployment of the airbag can occur. The same is true for the visible cover of the molding. The materials used for the visible cover should not impede airbag deployment as well as movement of the molding parts.
Therefore previously either a tear seam was introduced into the visible covers made of leather or leather-like material or, where desirable for aesthetic reasons, a desired tear line was introduced invisibly in the form of a back cut in the cover material. The depth of the back cut varied from a maximum value in the area of the desired tear initiation to a minimum value in the areas which are furthest removed from the tear initiation area of the tear line. The tools for making such a back cut are, however, expensive. In addition the tool guide is extremely complex, in particular with the setting of different cutting depths.
DE 195 16 230 C2 discloses an airbag cover having a tear line formed of a partial reduction of material thickness that is generated by removal of material from the cover. This removal can be made both on the side of the visible cover facing the molding and on the side facing away from the molding. Due to the material removal made in the visible cover, a geometry with a curving transition from non-weakened to weakened area is provided.
In DE 195 16 230 C2, the cover, which is partially reduced in thickness, is applied directly to a dimensionally rigid molding, as found for example, on a steering wheel. The forces acting on the visible cover, in particular in the area of the reduced material thickness, are absorbed by the adhesive layer applied between the molding and visible cover. The lateral distortion of the visible cover is minimized by the internal joint between the visible cover and the molding.
To improve the feel in the dashboard area and hence in the area of airbag covers, the leather or leather-like materials used as visible covers have been padded at least with one layer that has a greater softness than the comparatively rigid molding. Such materials are, for example, spacer fabrics, foams, fleece or similar materials. As stated above, these materials are covered with a leather or leather-like material, which, in the area of the desired tear line, has a back cut with a variable depth along the tear line. Due to the reduced ability of the layers of softer material to absorb the forces acting on the visible cover, for example under alternating climate loads or partial heating from intensive solar radiation, at least one further intermediate layer of a film-like material is used between the cover and molding. Intense material stress caused by these environmental effects, however, has proved visually unsatisfactory in use.